The present invention generally relates to environmental control systems and, more particularly, to a recirculating water extractor utilizing the Coanda effect and a method for water removal from an air stream passing through an aircraft environmental control system.
Environmental control systems are typically used in a closed area, especially an aircraft, to permit life to be sustained; the system generally provides the occupants of such closed area with a suitably controlled atmosphere to permit them to live and work in the area. An environmental control system of aircraft typically provides air supply, thermal control and pressurization for the passengers and crew, but may also provide avionics cooling, smoke detection, and fire suppression. On most aircraft utilizing jet engines, air is supplied to the environmental control system by being bled off a compressor of the jet engine upstream of the combustor. Temperature, pressure, and moisture content of this bleed air vary widely depending upon the thrust setting of the engine and the ambient conditions.
Compressed, warm, humid air, such as bleed air from a compressor stage of an aircraft gas turbine, is often transported into the environmental system of an aircraft. The compressed air is typically cooled with ambient air to near ambient temperature in an air-to-air heat exchanger and then expanded in an air cycle machine to provide a stream of cooled, conditioned air. When the air is cooled, water condenses. Therefore, the water entrained in the air must be removed from the air stream to protect rotating machinery and electronics. Excessive water in the air may also create passenger and pilot discomfort. Typically, the water is removed from the air by a water extractor, such as a conventional fixed vane centrifugal water separator. In many cases it is desirable to remove as much water as possible. Conventional water extractors typically may not collect all the water entrained in the air. Removing as much water as possible from the air using a water extractor as small and lightweight as possible would benefit the aircraft hardware, electronics, crew, passengers, and performance.
A water extractor of an environmental control system for removing water droplets entrained in an air stream has been described in U.S. Pat. No. 6,331,195B1. The water extractor includes a swirl section and a water collector section. Water droplets are captured by two sumps. Even though this water extractor is compact and efficient, the air may still contain entrained water after passing the described water extractor and it may be advantageous to remove even more of the water entrained from the air.
Another prior art patent, U.S. Pat. No. 6,752,845, describes an apparatus for separation of a liquid from a multiphase fluid flow flowing through a pipeline, wherein the fluid flow is separated into a central zone essentially containing gas, and an outer annular zone essentially containing liquid, and from which the gas and the liquid in the two zones are discharged via respective outlet means. The described apparatus includes a series of valves, which may be disadvantageous since valves are movable parts.
As can be seen, there is a need for a water extractor that removes more entrained water from an air stream passing through an environmental control system, for example, of an aircraft, than currently possible. Furthermore, there is a need for a compact and highly efficient water extractor that may be used in an environmental control system of an aircraft and that provides comfort to crew and passengers, protects machinery and electronics, and improves the aircraft performance. Still further, there is a need to eliminate movable parts from a water extractor by simplifying the design to eliminate production cost and to prolong the operating lifespan of the water extractor.